The insects are mostly scavengers and will feed on a wide variety of foods. They are especially fond of starches, sweets, grease, and meat products. In many locations, garbage is a principal food source.
Disease-producing organisms such as bacteria, protozoans, and viruses have been found on cockroach bodies. Different forms of gastroenteritis (food poisoning, dysentery, diarrhea, and other illnesses) appear to be the principal diseases transmitted by cockroaches. The organisms causing these diseases are carried on the legs and bodies of cockroaches and are deposited on food and utensils as the cockroaches forage.
Cockroach excrement and cast skins also contain a number of allergens to which many people exhibit allergic responses, such as skin rashes, watery eyes and sneezing, congestion of nasal passages, and asthma.